At present, a wide variety of animal and plant cells are cultured, and novel cell culture techniques are being developed. Cell culture techniques are conducted for the purpose of elucidation of biochemical phenomena and properties of cells, production of useful substances, and other purposes. In addition, inspection of physiological activity or toxicity of artificially synthesized drugs has been attempted with the use of cultured cells.
Some cells (many animal cells, in particular) have adhesion-dependent properties, such that they grow while adhering to other substances. Thus, such cells cannot survive for a long period of time if they are in suspension outside an organism. Culture of such adhesion-dependent cells necessitates the use of a support to which cells adhere, and a plastic culture dish that is evenly coated with a cell-adhesive protein, such as collagen or fibronectin, is generally used. Such cell-adhesive protein is known to react with cultured cells, facilitate cell adhesion, and influence cellular configurations.
Meanwhile, cell migration is associated with a variety of phases, such as immune response, embryonic morphogenesis after fertilization, and tissue repair and reproduction. Cell migration also plays a key role in progression of diseases such as cancer, atherosclerosis, and arthritis. Specifically, vascular endothelial cell migration is a critical phenomenon in pathophysiological conditions such as inflammation, atherosclerosis, and cancer metastasis. Accordingly, development of methods for cell migration assays in vitro has been attempted for a long period of time.
Examples of commercially available apparatuses used for cell migration assays include classic Boyden's chambers, cell culture inserts, FluoroBlock® (BD Biosciences), and Cell Motility HitKit® (Cellomics). With these apparatuses, however, it is difficult to control the direction of migration of adhered cells and quantitatively assay cell migration.
Non-Patent Document 1 describes a technique of controlling adhesion and non-adhesion of cells by applying an electric potential to a substrate that is not patterned and is conductive across its entire surface. However, such substrate is disadvantageous since the properties of its entire surface change upon application of an electric potential. Accordingly, such substrate cannot be used in a manner that allows cells to adhere thereto, a given region of the substrate is selectively modified to become cell adhesive, and the cells are controlled so that they migrate selectively to such cell-adhesive region.
Non-Patent Document 2 describes a method of cell culture comprising forming a non-cell-adhesive membrane on a base material comprising a conductive region and an insulating region provided thereon, applying an electric potential to a given conductive region to modify the non-cell-adhesive membrane into a cell-adhesive membrane, and allowing cells to adhere selectively to such region. In the conductive region of the substrate of Non-Patent Document 2, however, a cell-adhesive region is not adjacent to a non-cell-adhesive region. Even if cells are allowed to adhere to a region modified to become cell adhesive and another conductive region is modified to become cell adhesive with application of an electric potential, accordingly, cells that have already adhered to the substrate are unable to migrate to a non-adjacent region. Thus, assays cannot be carried out as intended.